"The number of new cases have fallen rapidly," Rafi Diallo, a Guinea health ministry spokesman, told Reuters. "Once we no longer have any new cases . . . we can say that it is totally under control."

Diallo said that 106 people have died in Guinea from 159 confirmed and suspected cases of Ebola since the start of the outbreak in February. Another 13 deaths have been reported in Liberia, from 26 confirmed and suspected Ebola cases, health officials noted.

The World Health Organization said that nearly 400 people who came into contact with an Ebola victim are currently being monitored.

On Monday, the U.S. Department of Defense opened a laboratory just outside Monrovia, Liberia to test of samples of suspected cases of Ebola. The International Federation of the Red Cross, Medecins Sans Frontieres, and other agencies are also helping to contain the outbreak.

There have been cases reported in Sierra Leone, Mali, and Ghana, but the WHO said none of them have been confirmed.

According to the WHO, this is the worst Ebola outbreak since 2007, when 224 people died in Uganda and the Democratic Republic of Congo. The first large-scale Ebola outbreak occurred in 1976, when 280 people died of the virus in the Democratic Republic of Congo.